U.S. patent number 9,550,174 [Application Number 13/810,557] was granted by the patent office on 2017-01-24 for mixed manganese ferrite coated catalyst, method of preparing the same, and method of preparing 1,3-butadiene using the same.
This patent grant is currently assigned to SK INNOVATION CO., LTD. The grantee listed for this patent is Young Min Chung, Ok Youn Kim, Tae Jin Kim, Yong Tak Kwon, Seung Hoon Oh. Invention is credited to Young Min Chung, Ok Youn Kim, Tae Jin Kim, Yong Tak Kwon, Seung Hoon Oh.
United States Patent |
9,550,174 |
Kwon , et al. |
January 24, 2017 |
Mixed manganese ferrite coated catalyst, method of preparing the
same, and method of preparing 1,3-butadiene using the same
Abstract
This invention relates to a method of preparing a mixed
manganese ferrite coated catalyst, and a method of preparing
1,3-butadiene using the same, and more particularly, to a method of
preparing a catalyst by coating a support with mixed manganese
ferrite obtained by co-precipitation at 10.about.40.degree. C.
using a binder and to a method of preparing 1,3-butadiene using
oxidative dehydrogenation of a crude C4 mixture containing n-butene
and n-butane in the presence of the prepared catalyst. This mixed
manganese ferrite coated catalyst has a simple synthetic process,
and facilitates control of the generation of heat upon oxidative
dehydrogenation and is very highly active in the dehydrogenation of
n-butene.
Inventors: |
Kwon; Yong Tak (Daejeon,
KR), Kim; Tae Jin (Daejeon, KR), Chung;
Young Min (Daejeon, KR), Kim; Ok Youn (Daejeon,
KR), Oh; Seung Hoon (Seoul, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kwon; Yong Tak
Kim; Tae Jin
Chung; Young Min
Kim; Ok Youn
Oh; Seung Hoon |
Daejeon
Daejeon
Daejeon
Daejeon
Seoul |
N/A
N/A
N/A
N/A
N/A |
KR
KR
KR
KR
KR |
|
|
Assignee: |
SK INNOVATION CO., LTD (Seoul,
KR)
|
Family
ID: |
45497243 |
Appl.
No.: |
13/810,557 |
Filed: |
May 26, 2011 |
PCT
Filed: |
May 26, 2011 |
PCT No.: |
PCT/KR2011/003861 |
371(c)(1),(2),(4) Date: |
January 16, 2013 |
PCT
Pub. No.: |
WO2012/011659 |
PCT
Pub. Date: |
January 26, 2012 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130158325 A1 |
Jun 20, 2013 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 20, 2010 [KR] |
|
|
10-2010-0069981 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C
5/48 (20130101); B01J 37/03 (20130101); B01J
37/088 (20130101); B01J 27/224 (20130101); B01J
37/0215 (20130101); C07C 5/3332 (20130101); B01J
23/8892 (20130101); C07C 5/3332 (20130101); C07C
11/167 (20130101); C07C 2523/889 (20130101); C07C
2523/34 (20130101); C07C 2527/224 (20130101); Y02P
20/52 (20151101); C07C 2521/04 (20130101); C07C
2523/745 (20130101); C07C 2521/08 (20130101) |
Current International
Class: |
B01J
27/224 (20060101); B01J 37/02 (20060101); B01J
37/03 (20060101); B01J 23/889 (20060101); C07C
5/48 (20060101); B01J 37/08 (20060101); C07C
5/333 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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S47-007920 |
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Apr 1972 |
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JP |
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2009028700 |
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Mar 2009 |
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WO |
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2009075478 |
|
Jun 2009 |
|
WO |
|
WO2009075478 |
|
Jun 2009 |
|
WO |
|
Other References
Papa, J.; Marzuka, S.; Brito, J. L.; Guaryan, N. Revista de la
Facultad de Ingenieria de la U.C.V., 2006, 21, 101-109. cited by
examiner .
Cavani, F. and Trifiro, F. Partial Oxidation of C2 to C4 Paraffins;
Baerns, M., Ed.; Basic Principles in Applied Catalysis;
Springer-Verlag: Berlin, Germany, 2004, pp. 19-85. cited by
examiner .
International Search Report, PCT/KR2011/003861, Feb. 22, 2012, 4
pages. cited by applicant .
Office Action in Chinese Patent Application No. 201180036201.1
dated Mar. 5, 2014, 12 pages. cited by applicant .
Qiu, Feng-Yan et al., Appl. Catal., 51 (1989) 235-253. cited by
applicant .
Welch, M. et al., Hydrocarbon Processing, 57(1 1), 131-136 (1978).
cited by applicant .
Office Action, Jan. 20, 2015, Japanese Patent Application No.
2013-520633. cited by applicant .
Office Action, Aug. 30, 2016, Korean Patent Application No.
10-2010-0069981. cited by applicant.
|
Primary Examiner: Li; Jun
Attorney, Agent or Firm: Abelman, Frayne & Schwab
Claims
The invention claimed is:
1. A method of preparing a mixed manganese ferrite coated catalyst
for use in preparing 1,3-butadiene, comprising: a) co-precipitating
a precursor aqueous solution comprising a manganese precursor and
an iron precursor while being mixed in a basic solution, thus
forming a co-precipitated solution; b) washing and filtering the
co-precipitated solution, thus obtaining a solid sample of mixed
manganese ferrite which is then dried at 70.about.200.degree. C.;
c) mixing the dried solid sample of mixed manganese ferrite, a
binder of alumina, distilled water and an acid at a weight ratio of
1:1.about.1,5: 8.about.10:0.4.about.0.6 at room temperature, thus
obtaining a mixture, wherein said alumina is boehmite and the acid
is selected from the group consisting of nitric acid, sulfuric
acid, hydrochloric acid and phosphoric acid; and d) adding a
support to the mixture obtained in c) and then performing blending
and drying, wherein said drying is performed at 50.about.80.degree.
C., and the support is silicon carbide.
2. The method of claim 1, wherein amounts of the manganese
precursor and the iron precursor are adjusted so that an atom ratio
of iron/manganese is 2.0.about.2.5.
3. The method of claim 1, wherein the precursor aqueous solution is
co-precipitated while being mixed in a 1.5.about.4,0 M basic
solution at 10.about.40.degree. C.
4. The method of claim 1, further comprising heat treating the
solid catalyst dried in d) at 350.about.800.degree. C.
5. The method of claim 1, wherein the support is a spherical or
cylindrical support having a size of 1.about.10 mm.
6. The method of claim 1, wherein the support is used in an amount
5.about.15times the weight of the dried solid sample.
7. The method of claim 1, wherein the alumina has a specific
surface area of 70.about.250m.sup.2/g.
Description
RELATED APPLICATIONS
This application is a U.S. national phase application under 35 USC
.sctn.371 of PCT/KR2011/003861 filed on May 26, 2011, and claims
the benefit under 35 USC .sctn.119 of Korean patent application
number KR 10-2010-0069981 filed Jul. 20, 2010, the disclosures of
which are incorporated herein by reference in their entireties.
TECHNICAL FIELD
The present invention relates to a mixed manganese ferrite coated
catalyst, a method of preparing the same, and a method of preparing
1,3-butadiene using the same, and, more particularly, to a method
of preparing a catalyst comprising coating a support with mixed
manganese ferrite obtained by co-precipitation at
10.about.40.degree. C., with the aid of a binder, and to a method
of preparing 1,3-butadiene by oxidative dehydrogenation of an
inexpensive crude C4 fraction containing n-butene, n-butane and
many other impurities without additionally extracting n-butene, in
the presence of the prepared catalyst.
BACKGROUND ART
Oxidative dehydrogenation of n-butene, which is used to produce
1,3-butadiene that is gradually increasing in demand in
petrochemical markets, produces 1,3-butadiene and water after
reacting n-butene with oxygen, and is thermodynamically favorable
because water, which is stable, is produced, and also the reaction
temperature may be reduced. If a C4 mixture or C4 raffinate-3
containing impurities such as n-butane is utilized as the supply
source of n-butene, the value of surplus C4 fractions may be
advantageously increased.
As mentioned above, the oxidative dehydrogenation of n-butene
(1-butene, trans-2-butene, cis-2-butene) is a reaction in which
1,3-butadiene and water are produced after a reaction between
n-butene and oxygen. Oxidative dehydrogenation, however, is
accompanied by many side-reactions, such as complete oxidations,
which are expected to occur because oxygen is used as the reactant,
and thus the development of catalysts which maximally suppress such
side-reactions and increase the selectivity for 1,3-butadiene is
regarded as of the utmost importance. The catalysts known to date
used in the oxidative dehydrogenation of n-butene include ferrite
based catalysts, tin based catalysts, bismuth molybdate based
catalysts, etc.
Among these, the ferrite based catalysts have different catalytic
activities depending on the kind of metal which occupies divalent
cation sites of a spinel structure, and furthermore, zinc ferrite,
magnesium ferrite, and manganese ferrite are known to be effective
in the oxidative dehydrogenation of n-butene, and zinc ferrite is
particularly reported as enabling there to be increased selectivity
for 1,3-butadiene compared to when using ferrite catalysts of other
metals [F.-Y. Qiu, L.-T. Weng, E. Sham, P. Ruiz, B. Delmon, Appl.
Catal., vol. 51, pp. 235 (1989)].
Reported in some patents and pieces of literature is the use of
zinc ferrite based catalyst in the oxidative dehydrogenation of
n-butene, in which in order to increase the reaction activity and
lifetime of the zinc ferrite catalyst used in the oxidative
dehydrogenation, pretreatment and post-treatment, including adding
an additive to the catalyst, are carried out, so that 1,3-butadiene
can be obtained in higher yield over a long period of time [F.-Y.
Qiu, L.-T. Weng, E. Sham, P. Ruiz, B. Delmon, Appl. Catal., vol.
51, pp. 235 (1989)/L. J. Crose, L. Bajars, M. Gabliks, U.S. Pat.
No. 3,743,683 (1973)/E. J. Miklas, U.S. Pat. No. 3,849,545
(1974)/J. R. Baker, U.S. Pat. No. 3,951,869 (1976)]. In addition to
the above zinc ferrite catalyst, the use of manganese ferrite
catalyst for oxidative dehydrogenation of n-butene is reported in
some patents.
In the oxidative dehydrogenation of n-butene, the zinc ferrite
catalyst is problematic because reproducibility may be deteriorated
by the addition of metal oxides used in order to prevent
inactivation and by the acid treatment, and also complicated
post-treatment procedures are required. Further, the manganese
ferrite catalyst should be maintained at high temperature upon
co-precipitation in order to exist in a pure spinel phase and
decreases the yield of 1,3-butadiene compared to when using zinc
ferrite.
In addition, the oxidative dehydrogenation of n-butene is
problematic because the yield of 1,3-butadiene is lowered when the
reactant contains a predetermined amount or more of n-butane [L. M.
Welch, L. J. Croce, H. F. Christmann, Hydrocarbon Processing, pp.
131 (1978)]. Thus, in the above conventional techniques, such
problems remain unsolved when oxidative dehydrogenation is carried
out using only pure n-butene (1-butene or 2-butene) as the
reactant. Hence, various pieces of literature or patents related to
catalysts and processes for producing 1,3-butadiene from n-butene
using oxidative dehydrogenation as above and processes based
thereon, including using pure n-butene as the reactant, are
disadvantageous because a separation process for extracting pure
n-butene from a C4 mixture should be additionally performed,
thereby drastically reducing economic efficiency.
DISCLOSURE OF INVENTION
Technical Problem
Accordingly, the present inventors have developed a method of
preparing a mixed manganese ferrite catalyst, which enables the
catalyst preparation process and the reproducibility of the
catalyst preparation to be simple and high and also exhibits high
activity for the oxidative dehydrogenation of n-butene in an
inexpensive C4 mixture (Korean Patent No. 0888143 (2009)). Although
such a mixed manganese ferrite catalyst, which is provided in the
form of pellets using tabletting, are highly active in the
oxidative dehydrogenation of n-butene in an inexpensive C4 mixture
without having to perform additional extraction, it makes it
difficult to control the generation of heat during the reaction,
undesirably limiting the suppression of side-reactions.
Therefore, an object of the present invention is to provide a
method of preparing a mixed manganese ferrite coated catalyst,
which is able to control the generation of heat to suppress
side-reactions, thus exhibiting very superior catalytic activity so
that 1,3-butadiene may be produced in high yield, and also in which
the preparation process of the catalyst is simple.
Another object of the present invention is to provide a method of
preparing 1,3-butadiene in high yield by performing oxidative
dehydrogenation using an inexpensive crude C4 mixture as a reactant
in the presence of the catalyst prepared by the above method.
Solution to Problem
In order to accomplish the above objects, an aspect of the present
invention provides a method of preparing a mixed manganese ferrite
coated catalyst, comprising a) co-precipitating a precursor aqueous
solution comprising a manganese precursor and an iron precursor
while being mixed in a basic solution, thus forming a
co-precipitated solution, b) washing and filtering the
co-precipitated solution, thus obtaining a solid sample which is
then dried, c) mixing the dried solid sample, a binder and
distilled water and an acid at a weight ratio of
1:0.5.about.2:6.about.12:0.3.about.0.8 at room temperature, thus
obtaining a mixture, and d) adding a support to the mixture
obtained in c) and then performing blending and drying.
Another aspect of the present invention provides a method of
preparing 1,3-butadiene, comprising a) supplying, as a reactant, a
gas mixture comprising a C4 mixture, air and steam, and b)
continuously passing the reactant through a catalyst bed to which
the catalyst prepared using the above method is fixed, so that
oxidative dehydrogenation is carried out, thus obtaining
1,3-butadiene.
Advantageous Effects of Invention
According to the present invention, when using a catalyst resulting
from coating a support having high heat conductivity with mixed
manganese ferrite obtained by coprecipitation at
10.about.40.degree. C. using a binder, it is possible to control
the generation of heat to facilitate the suppression of
side-reactions, so that 1,3-butadiene can be produced in high yield
from an inexpensive C4 mixture containing n-butene and n-butane
using oxidative dehydrogenation.
Also, the mixed manganese ferrite coated catalyst which has very
simple composition and synthetic route with excellent
reproducibility can be obtained. The use of the catalyst prepared
according to the present invention facilitates controlling the
generation of heat so that a crude C4 mixture containing a
high-concentration of n-butane can be used as a reactant for
oxidative dehydrogenation without requiring the additional
separation of n-butane thus enabling the preparation of
1,3-butadiene, and 1,3-butadiene can be obtained in high yield.
According to the present invention, 1,3-butadiene, which has a high
use value in the petrochemical industry, can be prepared from a C4
mixture or C4 raffiante-3 the use value of which is low, thus
achieving high added-value of the C4 fractions. Furthermore, an
independent production process for preparing 1,3-butadiene can be
ensured even without establishing a cracker, thus satisfying the
increasing demand for 1,3-butadiene, thereby generating economic
benefits, compared to conventional processes.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 illustrates the reaction results of Test Example 1 as shown
in Table 3 according to the present invention.
MODE FOR THE INVENTION
Hereinafter, a detailed description will be given of the present
invention.
The present invention pertains to the preparation of a mixed
manganese ferrite coated catalyst for use in the oxidative
dehydrogenation of n-butene, by synthesizing mixed manganese
ferrite using co-precipitation at 10.about.40.degree. C.,
particularly 15.about.30.degree. C., and then coating a support
with the mixed manganese ferrite using a binder, and to a method of
preparing 1,3-butadiene via the oxidative dehydrogenation of
n-butene using the catalyst thus prepared. As such, 1,3-butadiene
can be prepared from a C4 mixture which was not subjected to
additional n-butane separation.
The mixed manganese ferrite coated catalyst according to the
present invention for preparing 1,3-butadiene in high yield using
the oxidative dehydrogenation of n-butene is obtained by coating a
support having high heat conductivity with mixed manganese ferrite
which is an active material, so that the amount of mixed manganese
ferrite per the unit volume of the catalyst is small, thus
facilitating control of the generation of heat and exhibiting
higher activity and productivity for the oxidative dehydrogenation
of n-butene.
A manganese precursor and an iron precursor for synthesizing the
manganese ferrite include a chloride precursor or a nitrate
precursor, which dissolves well in distilled water which is useful
as the solvent. Specifically, the iron precursor is selected from
the group consisting of ferrous chloride tetrahydrate, ferrous
chloride hexahydrate, ferrous chloride dihydrate, ferric chloride
hexahydrate, ferrous nitrate hexahydrate, ferrous nitrate
nonahydrate, ferric nitrate hexahydrate, and ferric nitrate
nonahydrate.
The manganese precursor is selected from the group consisting of
manganous chloride, manganous chloride tetrahydrate, manganic
chloride, manganese tetrachloride, manganese nitrate hexahydrate,
manganese nitrate tetrahydrate, and manganese nitrate
monohydrate.
The amounts of the manganese precursor and the iron precursor are
adjusted so that the atom ratio of iron/manganese is 2.0.about.2.5,
and these precursors in such amounts are respectively dissolved in
distilled water, and then mixed together. If the atom ratio of
iron/manganese falls outside of 2.0.about.2.5, manganese is
difficult to interpose into iron lattices, or the activity of the
catalyst decreases drastically.
In order to co-precipitate the manganese precursor and the iron
precursor at room temperature, a 1.5.about.4 M basic solution, for
example, a 3 M sodium hydroxide aqueous solution, is separately
prepared. If the concentration of the basic solution is less than
1.5 M, it is difficult to form a mixed manganese ferrite catalyst
structure. In contrast, if the concentration thereof is higher than
4 M, in the case of a metal ion combined with a hydroxyl group, for
example, sodium hydroxide, it is difficult to remove a Na ion upon
washing, undesirably decreasing the activity. The case where the
molar concentration of the basic solution is adjusted to within the
range of 2.about.3 M is useful in terms of forming a mixed
manganese ferrite structure and performing post-treatment. The
basic solution used for co-precipitating the manganese precursor
and the iron precursor may include another type of basic solution
including ammonia water, in addition to sodium hydroxide. The pH of
the basic solution may fall in the range of 9.about.14.
To obtain the mixed manganese ferrite from the manganese precursor
and the iron precursor, the aqueous solution in which the manganese
precursor and the iron precursor were dissolved is introduced into
the basic solution at 10.about.40.degree. C. Stirring is performed
for 2.about.12 hours, in particular 6.about.12 hours so that the
introduction rate is maintained uniform and sufficient
co-precipitation takes place.
If the co-precipitation is carried out at a temperature lower than
10.degree. C., it becomes insufficient thus forming very unstable
bonds, undesirably causing side-reactions which are difficult to
control upon using a catalyst. If the temperature is higher than
40.degree. C., the catalytic activity may deteriorate. The
co-precipitation may be carried out at 15.about.30.degree. C.,
particularly 15.about.25.degree. C.
The stirred co-precipitation solution is phase separated for a
sufficient period of time so that the solid catalyst precipitates,
after which washing and filtering under reduced pressure are
performed, after which a precipitated solid sample is obtained.
The solid sample thus obtained is dried at 70.about.200.degree. C.,
particularly 120.about.180.degree. C. for 24 hours, thus preparing
mixed manganese ferrite.
The binder used to coat a support with the dried mixed manganese
ferrite may include alumina having a specific surface area of
70.about.250 m.sup.2/g. This alumina may use boehmite or alumina
sol as a precursor, and boehmite is particularly useful.
In the coating of the support with the mixed manganese ferrite, an
acid is added to gel boehmite, and may be selected from the group
consisting of nitric acid, hydrochloric acid, sulfuric acid,
phosphoric acid, and acetic acid.
The support which will be coated with the mixed manganese ferrite
may be selected from the group consisting of silicon carbide,
alumina or silica. Particularly useful is silicon carbide. The size
and the shape of the support may vary depending on the size of a
reactor used for the reaction, and are not limited but a spherical
or cylindrical support having a size of 1.about.10 mm may be
used.
The mixed manganese ferrite, boehmite, distilled water and nitric
acid are mixed at a weight ratio of
1:0.5.about.2:6.about.12:0.3.about.0.8, particularly
1:1.about.1.5:8.about.10:0.4.about.0.6. To this mixture, the
support is added in an amount 5.about.15 times, particularly
10.about.12 times the weight of mixed manganese ferrite, and
blended using a roll mixer and dried at 50.about.80.degree. C.,
thus obtaining a mixed manganese ferrite coated catalyst.
The dried mixed manganese ferrite coated catalyst is placed in an
electric furnace and heat treated at 350.about.800.degree. C.,
particularly 500.about.700.degree. C.
In the present invention, the X-ray diffraction peaks of the mixed
manganese ferrite used as the active material have the 2-theta
range of 18.78.about.18.82, 24.18.about.24.22, 33.2.about.33.24,
35.64.about.35.68, 40.9.about.40.94, 45.22.about.45.26,
49.56.about.49.6, 54.22.about.54.26, 55.24.about.55.28,
57.92.about.57.96, 62.56.about.62.6, 64.04.about.64.08,
66.02.about.66.06, 72.16.about.72.2, and 75.78.about.75.82. The
most remarkable peak is observed in the 2-theta range of
33.2.about.33.24.
In addition, the present invention provides a method of preparing
1,3-butadiene using a C4 mixture, which was not subjected to
additional n-butane separation, as the supply source of n-butene
via oxidative dehydrogenation in the presence of the mixed
manganese ferrite coated catalyst which was co-precipitated at room
temperature. The C4 mixture is selected from the group consisting
of 1-butene, 2-butene, and C4 raffinates-1, 2, 2.5, 3.
In Test Example 1 according to the present invention, a powder of
the catalyst is fixed to a straight type stainless steel reactor
for the catalytic reaction, and the reactor is placed in an
electric furnace so that the reaction temperature of the catalyst
bed is maintained constant, after which the reactants are reacted
while continuously passing through the catalyst bed of the
reactor.
The reaction temperature for oxidative dehydrogenation is
maintained at 300.about.600.degree. C., particularly
350.about.500.degree. C., more particularly 400.degree. C. The
amount of the catalyst is set so that the WHSV (Weight Hourly Space
Velocity) as the flow rate of reactants, is 1.about.5 h.sup.-1,
particularly 2.about.3 h.sup.-1, more particularly 2.5 h.sup.-1,
based on n-butene. The reactants include the C4 mixture and the air
and the steam at a ratio of 1:0.5.about.10:1.about.50, particularly
1:2.about.4:10.about.30. If the mixing ratio of the gas mixture
falls outside of the above range, a desired butadiene yield cannot
be obtained, or problems may occur due to drastic heat generation
when the reactor is operated.
In the present invention, n-butene and oxygen which are reactants
for the oxidative dehydrogenation are supplied in the form of a gas
mixture, and the amounts of the C4 mixture or the C4 raffinate-3
which is the supply source of n-butene and the air which is another
reactant are precisely controlled and supplied using a piston pump
and a mass flow rate regulator, respectively. In order to supply
steam which is known to alleviate the reaction heat of oxidative
dehydrogenation and to increase the selectivity for 1,3-butadiene,
water in a liquid phase is gasified while being introduced using a
mass flow rate regulator, so that the steam is supplied into the
reactor. The temperature near the inlet through which the water is
introduced is maintained at 300.about.450.degree. C., particularly
350.about.450.degree. C., whereby the introduced water is instantly
gasified and mixed with other reactants (C4 mixture and air), and
then passes through the catalyst bed.
Among the reactants which react in the presence of the catalyst
according to the present invention, the C4 mixture includes
0.5.about.50 wt % of n-butane, 40.about.99 wt % of n-butene, and
0.5.about.10 wt % of a C4 admixture which does not contain any
n-butane and n-butene. The C4 admixture without the n-butane and
n-butene includes for example isobutene, cyclobutane, methyl
cyclopropane, isobutene, etc.
When an inexpensive C4 mixture or C4 raffinate-3, including
n-butene, is subjected to oxidative dehydrogenation using the mixed
manganese ferrite coated catalyst according to the present
invention, 1,3-butadiene can be produced in high yield from
n-butene contained in the reactant.
Also when the support is used in the form of being coated with the
mixed manganese ferrite in the present invention, the amount of
mixed manganese ferrite which is the active material per the unit
volume of the catalyst is small thus making it easy to control the
generation of heat upon oxidative dehydrogenation, and the
composition and the synthetic route of the catalyst are simple,
advantageously ensuring reproducibility.
A better understanding of the present invention may be obtained in
light of the following examples which are set forth to illustrate,
but are not to be construed as limiting the present invention.
Preparative Example 1
Preparation of Tabletted Mixed Manganese Ferrite Catalyst
In order to prepare a tabletted mixed manganese ferrite catalyst,
manganese chloride tetrahydrate (MnCl.sub.2.4H.sub.2O) as a
manganese precursor, and iron chloride hexahydrate
(FeCl.sub.3.6H.sub.2O) as an iron precursor were used, both of
which were well dissolved in distilled water. 198 g of manganese
chloride tetrahydrate and 541 g of iron chloride hexahydrate were
dissolved in distilled water (1000 ml), mixed and stirred. After
sufficient stirring, the complete dissolution of precursors was
confirmed, and the precursor aqueous solution was added in droplets
to a 3 M sodium hydroxide aqueous solution (6000 ml) at 20.degree.
C. at a predetermined rate. This mixture solution was stirred at
room temperature for 12 hours using a stirrer so as to be
sufficiently stirred, and then allowed to stand at room temperature
for 12 hours so as to achieve phase separation. The precipitated
solution was washed with a sufficient amount of distilled water,
and filtered using a filter under reduced pressure thus obtaining a
solid sample which was then dried at 160.degree. C. for 24 hours.
The produced solid sample was heat treated in an electric furnace
at 650.degree. C. in an air atmosphere for 3 hours, thereby
preparing a manganese ferrite catalyst having a mixed phase. The
prepared catalyst phase was analyzed using X-ray diffraction under
the following conditions. The results are shown in Table 1 below.
As shown in Table 1, the catalyst prepared at room temperature was
confirmed to be mixed manganese ferrite containing iron oxide
(.alpha.-Fe.sub.2O.sub.3) and manganese iron oxide (MnFeO.sub.3).
In order to evaluate the activity thereof, the completed mixed
manganese ferrite catalyst was prepared into pellets using
tabletting, and milled to a size of 0.9.about.1.2 mm.
<Conditions for X-ray Diffraction>
X-ray generator: 3 kW, Cu--K.alpha. ray (.lamda.=1.54056 .ANG.)
Tube voltage: 40 kV
Tube current: 40 mA
2-theta measurement range: 5 deg.about.90 deg
Sampling width: 0.02 deg
Injection rate: 5 deg 2-theta/min
Divergence slit: 1 deg
Scattering slit: 1 deg
Receiving slit: 0.15 mm
TABLE-US-00001 TABLE 1 X-ray Diffraction Results of Mixed Manganese
Ferrite Catalyst 2-Theta 18.8 MnFeO.sub.3 24.2
.alpha.-Fe.sub.2O.sub.3 33.22 MnFeO.sub.3 35.66 MnFe.sub.2O.sub.4
40.92 MnFeO.sub.3 45.24 MnFeO.sub.3 49.58 MnFeO.sub.3 54.24
.alpha.-Fe.sub.2O.sub.3 55.26 MnFeO.sub.3 57.94 MnFe.sub.2O.sub.4
62.58 MnFe.sub.2O.sub.4 64.06 MnFeO.sub.3 66.04
.alpha.-Fe.sub.2O.sub.3 72.18 MnFe.sub.2O.sub.4 75.8
MnFe.sub.2O.sub.4
Preparative Example 2
Preparation of Extruded Mixed Manganese Ferrite Catalyst
Before the heat treatment was performed in Preparative Example 1, 5
g of dried mixed manganese ferrite, 50 g of boehmite, 30 g of
distilled water, and 3 g of nitric acid (60%) were mixed at room
temperature. This mixture was placed into an extruder and extruded
into a cylindrical form (diameter: 1 mm, length: 10 cm). The
extruded mixed manganese ferrite catalyst was placed in an electric
furnace, dried at 120.degree. C. for 2 hours, and then heat treated
at 650.degree. C. for 3 hours, thus completing a catalyst. The
completed catalyst was milled to a size of 0.9.about.1.2 mm as in
Preparative Example 1.
Preparative Example 3
Preparation of Mixed Manganese Ferrite Coated Silicon Carbide
Catalyst
Before the heat treatment was performed in Preparative Example 1, 5
g of dried mixed manganese ferrite, 5 g of boehmite, 50 g of
distilled water, and 3 g of nitric acid (60%) were mixed at room
temperature. This mixture was added with 50 g of spherical silicon
carbide having a diameter of 1 mm, and blended using a roll mixer
and dried at 60.degree. C. The dried mixed manganese ferrite coated
silicon carbide catalyst was placed in an electric furnace, and
then heat treated at 650.degree. C. for 3 hours, thus completing a
catalyst.
Example 1
Oxidative Dehydrogenation of C4 Raffinate-3 or C4 Mixture Using
Mixed Manganese Ferrite Coated Silicon Carbide Catalyst
Using the mixed manganese ferrite coated silicon carbide catalyst
of Preparative Example 3, oxidative dehydrogenation of n-butene was
carried out. The specific reaction conditions are described
below.
The reactant used for the oxidative dehydrogenation of n-butene was
a C4 mixture. The composition thereof is shown in Table 2 below.
The C4 mixture was supplied in the form of a gas mixture along with
air and steam, and a straight type fixed-bed reactor made of
stainless steel was used.
The ratio of reactants was set based on n-butene in the C4 mixture,
so that the ratio of n-butene:air:steam was 1:3:20. The steam was
obtained by gasifying water in a liquid phase at 350.degree. C.,
mixed with the other reactants including C4 mixture and air, and
then fed into the reactor. The amount of C4 mixture was controlled
using a pump, and the amounts of air and steam were regulated using
a mass flow rate regulator.
The amount of the catalyst was set so that the WHSV as the flow
rate of the reactants was 2.5 h.sup.-1 based on n-butene in the C4
mixture. The reaction temperature was maintained so that the
temperature of the catalyst bed of the fixed-bed reactor was
400.degree. C. The reaction product was composed of, in addition to
the desired 1,3-butadiene, carbon dioxide which is a byproduct of
complete oxidation, a cracking byproduct, and an isomerization
byproduct, and n-butane contained in the reactant, and was
separated and analyzed using gas chromatography. When using the
mixed manganese ferrite catalyst for oxidative dehydrogenation of
n-butene, the conversion of n-butene, and the selectivity and yield
of 1,3-butadiene were calculated according to Equations 1, 2 and 3
below.
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times..times..times..times..times..times..times..times..times..times..-
times..times..times..times..times..times..times..times..times..times..time-
s..times..times..times..times..times..times..times..times..times..times.
##EQU00001##
TABLE-US-00002 TABLE 2 Composition of C4 Mixture used as Reactant
Composition Molecular Formula Weight % i-Butane C.sub.4H.sub.10 0
n-Butane C.sub.4H.sub.10 26.8 Methyl Cyclopropane C.sub.4H.sub.8
0.1 trans-2-Butene C.sub.4H.sub.8 44.1 Butene-1 C.sub.4H.sub.8 6.6
Isobutylene C.sub.4H.sub.8 0 cis-2-Butene C.sub.4H.sub.8 21.9
Cyclobutane C.sub.4H.sub.8 0.5 i-Pentane C.sub.5H.sub.12 0 Total
100
Test Example 1
Reaction Activities of Mixed Manganese Ferrite Coated Silicon
Carbide Catalyst, Extruded Mixed Manganese Ferrite Catalyst and
Tabletted Mixed Manganese Ferrite Catalyst
The catalysts of Preparative Examples 1.about.3 were applied to the
oxidative dehydrogenation of a C4 mixture according to the reaction
of Example 1. The results are shown in Table 3 below and FIG. 1.
The case where the mixed manganese ferrite coated silicon carbide
catalyst was used could result in an 80% conversion of n-butene, a
95.5% selectivity for 1,3-butadiene, a 76.4% yield of
1,3-butadiene, and also changes in temperature of the catalyst bed
were 10.degree. C. or less, from which the generation of heat was
evaluated to have been efficiently controlled.
TABLE-US-00003 TABLE 3 Preparative n-Butene 1,3-Butadiene
1,3-Butadiene .DELTA.T Example Conversion (%) Selectivity (%) Yield
(%) (.degree. C.) 1* 70 91.5 64.1 100 2* 59 92.8 54.8 11 3 80 95.5
76.4 7 *Comparative Preparative Example
As is apparent from Table 3, the extruded mixed manganese ferrite
catalyst had low changes in temperature, but exhibited
comparatively low conversion and yield because of the small number
of active sites of the mixed manganese ferrite exposed so as to
function efficiently as an actual catalyst.
In the case of the mixed manganese ferrite coated silicon carbide
catalyst obtained by coating silicon carbide having a small
specific surface area and a small pore volume with mixed manganese
ferrite, the mixed manganese ferrite that is the active material is
entirely exposed near the surface of the catalyst and thus can
exclusively function as the active sites of the catalyst. Whereas,
in the case of the extruded catalyst, active sites are combined
with alumina having a large specific surface area and a large pore
volume and are present not only on the surface of the catalyst but
also in the pores and thus are not exposed and cannot act as active
sites. Even when extrusion is performed using manganese ferrite of
the same amount, the activity is not exhibited as in the coated
catalyst. Therefore, the mixed manganese ferrite coated silicon
carbide catalyst can manifest higher conversion or selectivity and
can very efficiently control the generation of heat, compared to
the mixed manganese ferrite catalysts of comparative preparative
examples.
Although the embodiments of the present invention have been
disclosed for illustrative purposes, those skilled in the art will
appreciate that a variety of different modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying claims.
Accordingly, such modifications, additions and substitutions should
also be understood as falling within the scope of the present
invention.
* * * * *